That's the ARC file unpacker. The ARC files are what contain all the 3D models. Cracked in one day by me, although it may be buggy. If yah want the source, you'll have to wait one week - that's my policy.
Now, I can focus on the extracted models =P
WARNING: I did this from 1AM to 7AM - there's GOT to be idiotic little bugs somewhere which I didn't notice due to my bloodshot eyes
The models are in the PSPM files btw, and you need a vertex buffer program to view em for now.
The PSP might just have its own FPS modding community ;P